Ore reducing and digesting process



Jan. 30, MQRELAND ORE REDUCING AND DIGESTING PROCESS Original Filed Nov. 17, 1936' "INVENTOR.

ATTORNEYS.

Patented Jan. 30, 1940 UNITED STATES PATENT OFFICE Application November 17, 1936, Serial No. 111,261 Renewed May 22, 1939 6 Claims.

The present invention relates to improvements in an ore reducing or digesting process and its principal object is to provide a process for decomposing, transposing, dissolving, internally rematerials or other bodies, whether in the raw state or in the roasted, fused, leached or other-' 10 wise treated state.

It has been proposed heretofore, to carry on a digesting process of the character described in open or closed vessels in the presence of a suitable acid, such as sulfuric acid, or in certain in- 16 stances hydrochloric acid or nitric acid, depending upon the nature of the material under treatment, at high temperatures and under both high and low pressures.

It has been found,however, that the pressure 90 which normally is produced in the closed vessel during certain periods of the reaction, at the temperatures most desirable, becomes excessive, that is greater than is necessary for the reaction, and calls for such structural strength in the con- 15 struction of the vessel and the sealing means as" is diflicult to obtain.

One of the objects of the present invention is to effect a reduction in the pressure which would normally be produced in the vessel by carrying on a process of condensation along with the diseparately from the material to bedigested to, produce hot acid vapors and if these vapors 'are fed into the separately arranged material for carrying out the process. I a

It is a iurther object. of my invention, therefore, to change the conventional process of digest;-

ing by separately heating a body of acid for pro- 60 ducing hot acid vapors andby using the vapors as an agent for carrying out the digesting process.

A further object of, the present inventionis'to reduce the time necessary for carrying out the digesting process and to obtain a better control 3 over the process at all times by gradually introducing the material to be digested, preferably in measured quantities, into the vessel or chamber whichhas previously been charged with hot acid vapors or fumes so that a more immediate reaction takes place between the material and the hot 5 vapors, the feeding of the latter being continued with the feeding of the material to be treated.

A further object of the invention is to provide a method for regulating the condensing eifect previously discussed, depending upon the pressures developed by a certain quantity of material under treatment.

And finally it is proposed in the present invention to'render the digesting process more effective by stirring and agitating the material under treatment for effecting a more thorough interaction between the hot acid fumes and the material.

Further objects and advantages of my invention will appear as the specification proceeds.

My invention may be carried out in many different ways and by different agencies and apparatus and I desire to be protected, in this application, on the process, regardless of any apparatus by means of which it may be executed. To facilitate the understanding of my invention, however, I have developed a preferred form of apparatus, which is described and claimed in my co-pending application, Serial Number 111,260, filed November 1'7, 1936, and which I will use in the present application as a means for illustrating the preferred manner of executing my invention.

The apparatus by means of which my improved process may be carried out is illustrated in the accompanying drawing, in which Figure 1 shows a central vertical section through the apparatus, and

Figure 2 a diagrammatic plan view of a modified form of the apparatus. 7

While I have shown only the preferred form for 40 carrying out my process it should be understood that various changes or modifications may be made in the apparatus and in the arrangements of the various steps of my process without departing from the spirit of the invention.

Referring to the drawing in detail, 'the vessel or pot I is revolvably mounted in the furnace 2 by means of trunnions 3 projecting from the vessel and having bearing in the wall of the furmice. The vessel comprises a body section 4 and 5 a removable top 5. The body section comprises two compartments, an upper compartment 6 and a lowercompa'rtment I, the two compartments being formed integralwith one another.

The upper compartment is intended to contain the material to be treated. The lower compartment is intended to hold the acid used in the treatment of the material and it is separated from the upper compartment by means of a grate 8 which is supported on a transverse bar 8 arranged on top of the lower compartment. The grate may be formed integral with the vessel, if desired.

A burner lil of any suitable construction is' provided for heating the two compartments and the products of combustion are discharged through the vent l2. A pyrometer l3 indicates the temperature of the furnace.

For discharging treated material from the vessel the latter may be tilted by any suitable means as by the pinion l4 engaging with a rack l5 formed on the outside of the vessel. The furnace is arranged in a conventional manner, with a removable wall to permit of the tilting movement of the vessel.

The top 5 has a flange l6 bolted to the upper edge of the body section as at I! and the connection is made gas tight by means of a tongue and groove arrangement I8 with an interposed Washer 19. The flange l6 also rests on the top edge of the furnace to serve as a closure for the same.

The top 5 has a vapor tube 20 projecting therefrom and this tube is of considerable height, preferably 12 to 15 feet, and some 8 to inches in diameter. These dimensions, of course, are subject to change, provided that they are proportioned to accomplish the object of the vapor tube, namely, to condense vapors rising thereinand to feed the condensed vapors back into the main body of the vessel.

The tube is preferably made of heat conducting material and does not need any insulating lining, although, of course, such lining may be provided for protecting the material of the tube or for lessening or regulating the condensing effect.

It will be noted that the condensing and the feeding back of the products of condensation tend to .keep down the pressures prevailing inside the vessel and thus constitute an automatic control for such pressures. It is apparent that the tube may be designed, relative to the size of the vessel,

the quantity of material to be treated therein and the normal intensity of heat applied to produce, under given conditions, a desired result and a desired condensing effect, for maintaining a desired pressure in the vessel.

To render the operation more flexible, a plurality of vapor tubes 2! may be substituted for the single tube of Figure 1, as shown in Figure 2, and such tubes may rise from the top of from the side of the vessel, as indicated, and some or all of them may be provided with valves for rendering some active and some inactive depending upon the condensation effect desired.

In Figure 1 the tube is shown as rising from the center of the top, and if it is mounted in this position, it may be used as a supporting medium for the agitator shaft 2|, the lower end of which may. take bearing on the bar 9 or on the grate 8, if the latter is formed integral with the vessel, while its upper end extends through the closed end 22 of the tube, suitable packing being provided as at 23.

The shaft is formed with propeller blades 24, of any suitable type which are preferably formed to scrape the wall of the vessel' and to have a general lifting effect. This shaft may be rotated by any suitable means, as by the belt 25.

The agitator may be omitted where its time'- tion is not necessary or not desired and any other agitating means may be substituted, as for instance, air agitation through connections indicated at H and 26.

The acid may be fed into the lower compartment through the aperture 21, normally closed by a valve 39; and the material to be treated maybe passed into the upper compartment through the chute 28 which is controlled by a rotary feed valve 29 which is cupped as shown at 30 to feed the material in measured quantities while maintaining a perfect seal for the vessel.

A thermometer 3| may be mounted on top of the vessel in' a well 3| and suitable pressure gauges and relief valves 32 and 33 may be mounted on top of the vessel and at the upper end of the vapor tube. Eye bolts 34 are provided on the top to permit the latter with the tube and the attachments to be lifted from the vessel. The lower compartment is formed with projecting lugs 36 which come to rest on the foundation 3'! when the vessel is in normal working position.

Figure 2 diagrammatically shows certain modiflcations of the arrangement of'the main figure. It shows a purality of vapor tubes 20' which may emanate from the top of the vessel or from the side thereof and which may be provided with cutoff valves 20". It also illustrates an acid chamber 'I' mounted separately from the main chamber 6' and suitably connected thereto by a conduit 38 through which the fumes are discharged into the main vessel. The conduit may be controlled by a valve 38'. The agitator shaft 2| is here shown as being separate from the vapor tubes.

In carrying out the process, a suitable quantity of acid is poured into the lower compartment. Heat is applied through the burner l0 and, as the vapors of the acid rise into the upper chamber, the material is fed into the latter in measured quantities by means of the rotary valve 29. The agitator may be used as desired. The fumes from the acid thus mix with the material to be treated and the latter is now subjected to a digesting process in the presence of the fumes.

On account of the high temperatures used which should be at least equal to cr m excess of theboiling point of the acid, but vapors are formed which increase the pressure within the vessel and this pressure would become excessive, which means that it would become greater than is required for the digesting process and would call for much stronger construction than is desirable, if it were not for the vapor tube or tubes. The latter, however, permit the vapors to rise therein and to condense whereby excess pressures are avoided. The condensed vapors are fed back into the vessel so that there is no loss or waste.

It is apparent that the entire process is thus under the control of the operator who may regulate the feed of the material through the valve 29, the agitation by regulating the speed of the agitator or the amount of air injected through the air inlets H and 26, and where the apparatus of Figure 2 is used, the amount of acid fumes admitted throughthe valve 38' and finally the degree of condensation by opening or closing of fully treated by my process I might mention cassiterite, orthoclasemuscovite, mica, magnetic oxid of iron, (FeaOr) tin dioxid (SnOz) all titanites, sulfids of cobalt nickel, antimony, bismuth, and mercury, manganese oxids (M1102), etc., chromite (FeOCraOa), silicates of copper, of nickel, of zinc, of potassium and of other metals, barium sulfate (B3504), cinnabar (HgS) and other sulfids, as well as ignited, sintered, roasted, melted, smelted, leached or otherwise treated ores or substances, such as ignited ferric oxid, ignited alumina, ferrites, alloys, certain molecular'compounds and other unusual and dimcultly soluble freak bodies.

I claim:

1. The method of reducing or digesting material of the character described, which comprises heating the material in' a closed vessel under pressure, in the presence of pre-generated acid fumes, while exposing a limited portion of gases produced in the process to a cooling medium for condensation and for reduction of the pressure in the vessel, and returning the condensed vapors directly to the portion of the vessel in which the reaction is taking place.

2. The method of reducing or digesting material of the character described, which comprises the pulverizing of the material and heating the pulverized material in a closed vessel under pressure, in the presence of pre-generatedacid fumes, while mechanically agitating the material, and while partially condensing vapors produced during the reaction for preventing excessive pressure, and returning the condensed acid vapors directly to the portion of the closed vessel in which reaction is taking place.

3. The method of reducing or digesting material of the character described, which comprises introducing hot acid vapors into a closed vessel, applying heat to the vessel, and gradually feedin material into the vessel in a direction countercurrent to that in which the acid vapors are introduced, while maintaining the vessel in a sealed condition.

4. The method of reducing or digesting material of the character described, which comprises introducinghot acid vapors into a closed vessel from the bottom of the latter, applying heat to the vessel and gradually feeding the material into the vessel through the top of the vessel in measured quantities, while maintaining the vessel in a sealed condition.

5. The method of reducing or digesting material of the character described, which comprises heating acid in one vessel to produce hot acid vapors, conducting the hot vapors into a second vessel and digesting the material in the second vessel with the vapors, in the presence of heat and under pressure, while partially condensing gaseous substances within the second vessel formed during the reaction for preventing the pressure from reaching an excessive degree, and while returning the products of condensation to the material.

6. The method of reducing or digesting mate rial of the character described, which comprises the heating of acid in one vessel to produce hot acid vapors, applying heat to a second vessel, and gradually introducing the material into the second vessel in a direction countercurrent to that which the acid vapors are introduced, while maintaining the second vessel in a sealed condition for reaction of the material with the vapors in the presence of heat and under pressure.

RICHARD K. 'MORELAND. 

